Hey there ZivtheAwesome,
It sounds like you are are experiencing a few issues after the update to iOS 8. First to troubleshoot Siri, I would turn it off then restart the iPad, turn it back on and test it out:
iOS: Troubleshooting Siri
If Siri is not behaving as expected, try toggling Siri off and then back on. You can turn it off and on in Settings > General > Siri.
There is a sound associated with locking the device called Lock Sounds which you can disable in your Settings:
iOS: Understanding sounds, ringtones, and alerts
To change sound settings: Go to Settings > Sounds
And to troubleshoot the Skype app, you can use the following article to help with that, but there may also be a setting for the sound in Settings:
iOS: An app you installed unexpectedly quits, stops responding, or won’t open
Thank you for using Apple Support Communities.
Take care,
Sterling